Method of simultaneously finishing cluster gears



May 14, 1940. o. e. SIMMQNS METHOD OF smuummousm FINISHING CLUSTER GEARS s sheets-shes; 1-

Filed Sept. 13. 1935 5 m m E aw m I y 14, 1940- o. s. SIMMbNS 2,200,584

METHOD OF SIMULTANEOUSLY FINISHING CLUSTER GEARS Filed Sept. 13, 1935 3 Sheets-Sheet Z imm ym May 14, 1940. o. e. SIMMONS METHOD OF SIMULTANEOUSLY FINISHING CLUSTER'GEARS Filed Sept. 13, 1935 3 Sheets-Sheet 3 i Jrms/vroe O4 lVEE G 5/MMON5 firramvsvs Patented May 14, 1940 UNHTFED STATES PATENT OFFICE METHOD OF SIMULTANEOUSLY FINISHING CLUSTER GEARS 1 Claim.

This invention relates to a method of finish- .ing the gears of cluster gears by subjecting the same to a combined burnishing and shaving operation.

The method disclosed herein relates in its broadest aspects to the method of finishing gears by a combined burnishing and shaving operation, such as is disclosed in my copending application Serial No. 9,824, filed March '7, 1935, which has become Patent No. 2,137,146.

An object of the invention is to provide an improved and novel method for finishing cluster gears with a high degree of accuracy and with the desiredsurface smoothness, compactness and finish.

Another object is to provide an improved and novel method for simultaneously finishing all of the gears of a cluster gear with a high degree of accuracy and with the desired surface smoothness, compactness and finish.

A further object is to provide a method of finishing cluster gears which requires a minimum amount of time for the operation and which, therefore, increases production and materially lowers the cost thereof.

Another object is to provide a method of finishing cluster gears which assures accurate concentricity in all of the gears of the cluster.

Another object is to provide an improved and ac novel method for finishing cluster gears quickly and economically and with a high degree of accuracy and the desired surface smoothness, compactness and finish by means of a combined and simultaneous burnishing and shaving operation.

Another object is to provide an improved and novel method for simultaneously finishing the individual gears of a cluster gear with a high degree of accuracy and the desired surface smoothness, compactness and finish by means of simul 140 taneously subjecting all of the gears of the cluster to a combined burnishing and shaving operation.

Further and additional objects and advantages residing in the invention will become apparent during the detailed description that is to follow of an embodiment of the invention.

Referring to the accompanying drawings,

Fig. 1 is an end elevational view of a cluster gear being finished in accordance with the present invention, wherein each individual gear of 50 the cluster rotates in mesh with a plurality of combined burnishing and shaving cutters.

' Fig. 2 is a sectional view taken substantially on line 2-2 of Fig. 1 looking in the directionof the arrows.

Fig. 3 is a perspective view of a combined burnishing and shaving cutter in the form of a helical I gear and corresponds to the cutters shown in Figs. 1 and 2, and

Fig. 4 is a perspective view of a combined burnishing and shaving cutter in the form of a spur 5 gear.

The present requirement for gears of high accuracy and finish, especially gears which are to be used in motor vehicles, has necessitated further finishing operations upon the gears after lo they have been cut. This further finishing of the gears has been carried out heretofore by means of a number of separate operations, namely, by a shaving operation to remove and correct irregularities and errors in the gear teeth occasioned by inaccurate cutting of the gears, and by a separate burnishing operation to compact, smooth and polish the working face surfaces of the gear teeth. It will be evident that the practice involving separate shaving and burnishingzo operations, is necessarily slow and uneconomical.

Machines have been produced and are now being used for the purpose of subjecting the gears to the shaving operation referred to. However, these machines generally impart to the work gears and to the tools or cutters compounded relative movements, usually consisting of relatively rotating the work gears and cutters in mesh and at the same time imparting to the cutters and work gears relative lateral'and linear movements. to produce the shaving action of the cutters upon the work gears. Certain of the machines referred to are constructed so that the axes of the cutter and work gear are arranged in non-paral-. lel relationship, wherefore the cutter has merely a tangential point contact with the work gear.

It is necessary in such machines to impart long relative linear and lateral movements to the cutter and gear axially of the latter to cause the cutter to contact the gear from end to end to 0 cut cylindrical surfaces thereon.

The machines referred to above are not adapted to operate upon the smaller gears of cluster gears because of the necessary lateral and linear movements of the cutter completely across the face of the gears, inasmuch as the larger gears of the cluster would interfere with such move ments.

Heretofore it has been necessary to separately finish the individual gears of a cluster irrespec tive of the character of finishing operations employed thereon, with the result that the total time consumed in the finishing of all of the gears of a cluster gear is extremely long and hence materially increases production costs.

In addition to the great time and large production cost incident to separately finishing the individual gears of a cluster, there arises a further disadvantage in that the individual or separate gears of the cluster so finished are apt not to be truly concentric with each other, since they have been individually finished by separate finishing operations.

The present invention contemplates a method of finishing cluster gears accurately, efficiently and with the desired smoothness, and compactness of the working face surfaces of the teeth of the gears by means of a combined and simultaneous burnishing and shaving operation.

The invention further contemplates simultaneously finishing all of the individual gears of a cluster by means of a combined and simultaneous burnishing and shaving operation, wherefore the finishing operation consumes a minimum amount of time, with a resultant reduction in production costs, and since it is carried out simultaneously upon all of the gears of the cluster it substantially assures that the individual gears of the cluster will all be truly concentric with respect to each other.

As previously stated, the method of the present invention in its broad aspect corresponds to the method disclosed in my said copending application Serial No. 9,824, and the combined burnishing and shaving cutters employed in carrying out the method are identical with the cutters illustrated and described in said application Serial No. 9,824.

In carrying out the present method the individual gears of a cluster are each rotated in mesh with a plurality of combined burnishing and shaving cutters of gear form corresponding to the form of the individual gears of the cluster, it being understood that a suitable pressure feed movement is imparted between the cutters and the work or individual gears.

The cutters employed in carrying out the method are of gear form corresponding to the form of the work gears and may have either helical, straight or other forms of teeth. The cutters are provided around their circumferences with a multiplicity of helical grooves extending from end to end of the cutters in an axial direction and completely through the teeth thereof from the outside diameters of the cutters to the roots of the teeth, whereby the teeth of the cutters are provided with a multiplicity of cutting edges which act, when the cutters are rotated under pressure in mesh with the individual gears of the cluster, to shave the complete working face surfaces of the teeth of the individual gears from end to end thereof, while the working face surfaces of the teeth of the cutters between the helical grooves form burnishing lands which act simultaneously with the shaving action to burnish the working face surfaces of the teeth of the individual gears of the cluster. The multiplicity of circumferential grooves may be either in the form of a plurality of separate helical grooves or in the form of a single helical groove of small lead and many spires.

Since the cutters are provided with a plurality or multiplicity of such circumferential helical grooves the shaving bites or'cuts taken in the individual gears of the cluster'by the large number of cutting edges formed by the helical grooves will overlap and because of the lead of the helical grooves will migrate from end to end of the working face surfaces of theteeth'ofthe individual gears In view of the fact that the cutters are provided with a plurality of circumferential helical grooves having a lead axially of the cutters and extending completely through the teeth thereof from the outside diameters of the cutters to the roots of the teeth, only a relative rotative movement in addition to a radial pressure feed movement need be imparted to the cutters and the individual gears of the cluster to effect the simultaneous shaving and burnishing of the entire working face surfaces of the teeth of the individual gears from end to end thereof, wherefore it is possible to simultaneously finish all of the individual gears of the cluster.

Referring first to Fig. 3 of the drawings, there is illustrated a combined burnishing and shaving cutter ID in the form of a helical gear. The cutter I0 is provided with a multiplicity of circumferential helical grooves ll extending around the cutter and completely through the teeth thereof from the outside diameter of the cutter to the roots of the teeth. The multiplicity of grooves II are illustrated in the form of a plurality of separate helical grooves, but it will be understood that the grooves in the cutter might be in the form of a single helical groove of small lead and many spires, inasmuch as the object of the grooves is to form a multiplicity of small cutting and burnishing teeth in each tooth of the cutter.

The circumferential helical grooves II should extend from end to end of the cutters in an axial direction and should be of such lead that a plurality or multiplicity of the grooves are provided, whereby a great number of cutting edges [2 and I3 are formed on both of the working face surfaces of each tooth of the cutter. As fully explained in my copending application Serial No. 9,824, and to which reference should be had, the number of cutting edges l2 and I3 provided on the cutter by the grooves II, results, when the cutter is rotated in mesh with the work gear and under pressure, in having the shaving cuts or bites taken in the working face surfaces of the teeth of the work gear overlap and migrate from end to end of the work gears. of cutting or shaving edges l2 and 13 reduces the cutting or shaving force which must be applied to the cutters in shaving the work gear.

As previously stated, the grooves H extend completely through the teeth l4 of the cutter from the outside diameter D thereof to the roots R of the teeth. The teeth M are divided by the grooves II from end to end of the cutter into a plurality of separate small cutting and burnishing teeth, each of which has two acute shaving or cutting edges l2 and two obtuse shaving or cutting edges l3. The working face surfaces of the teeth l4 between the grooves ll form a plurality of burnishing surfaces or lands, which when the cutter is rotated in mesh with the work gear under pressure, act to burnish the working face surfaces of the teeth of the work gear from end to end thereof simultaneously as they are being shaved by the cutting or shaving edges l2 and 13.

In Fig. 4 a cutter l5 of spur gear form is illustrated and said cutter is provided with a multiplicity of circumferential helical grooves l6 similar to the helical grooves H in the cutter l0 and extending completely through the teeth I! of the cutter from the outer diameter D thereof to the roots R of the teeth. The grooves IE, it will be understood, divide the teeth I! of the cutter l5 into a plurality of separate shaving and burnishing teeth, each of which is provided with two acute cutting edges l8 and two obtuse cutting edges l9.

In carrying out the method of the present in- The large number vention the individual gears of the cluster gear are rotated in mesh under pressure with a plurality of combined burnishing and shaving cutters, such as shown in Fig. 3 or 4, of gear form corresponding to the form of the individual gear. In those instances where the individual gears of the cluster gear are helical gears said gears may be of either hand and may haveany desired angle of helix, normal diametral pitch, normal pressure angle and number of teeth. The cutters employed for finishing the helical individual gears will be in the form of helical gears of the opposite hand from the individual gears but of the same angle of helix, normal diametral pitch and normal pressure angle as the individual gears.

Figs. 1 and 2 of the drawings illustrate the manner in which the method is employed in the finishing of the individual helical gears of a gear cluster, and further shows how the method may be used to simultaneously finish all of the individual gears of the cluster.

It will be understood that the method can be carried out by means of various forms of apparatus and that the fragmentary showing of apparatus in, Figs. 1 and 2 is merely for the purpose of illustration. The arm 29 of a suitable machine has a laterally extending portion providing a bearing for the reduced end of the driven shaft 2|. The reduced portion of the driven shaft M has mounted thereon a plurality of combined burnishing and shaving cutters 22, 23, 24 and 25 of diiferent sizes and corresponding in construction to the cutter l shown in Fig. 3. The cutters 22, 23 and 25 are so mounted on the driven shaft 2! as to be freely rotatable thereon, while the cutter 24 is keyed to said shaft so as to be driven thereby. It will be understood, of course, that the cutters 22, 23, 24 and 25 are maintained in properly spaced position axially of the shaft 2i and that if desired any one of the cutters might be the driven cutter in place of the cutter 24, in which event the latter cutter would be freely rotatable on the shaft and act as an idler.

The apparatus also includes a support 26 located to one side of the arm and carrying spaced shafts 2'! which are parallel to each other and to the shaft 2|. Suitable mechanism is provided for moving the support 26 toward and away from the arm 20 in order to produce the desired radial pressure between the cutters and the cluster gear. Each of the shafts 27 has mounted thereon freely rotatable cutters 22, 23, 24 and 25, corresponding to the cutters on the shaft 2!, it being noted, however, that the cutters 24 on the shafts 21 are not keyed to said shafts but freely rotate thereon, as do also the cutters 22, 23 and 25.

The cluster gear 28 comprises the individual helical gears 29, 3!], 3| and 32, which individual gears during the finishing operation rotate in mesh with the sets of cutters 22, 23, 24 and 25, respectively, it being noted that each of the individual gears therefor rotates in mesh with three cutters. The cluster gear 28 is arranged in floatlng, intermeshing engagement with the cutters, it being noted that said cluster gear is merely positioned between the cutters and is held against axial movement by having one of its ends engaging an anti-friction abutment collar 33 mounted on a rod 34, while its opposite end engages asimilar abutment collar 35 carried by an adjustable and removable rod 36.

The size'of the cutters 22, 23, 24 and 25 is in inverse order with respect to the size of the individual gears of the cluster, it being noted that the smallest individual gear 29 of the cluster is operated on by the cutters 22 which are the largest of the cutters, while the largest individual gear 22 of the cluster is operated on by the cutters 25 which are the smallest of the cutters.

In carrying out the method the support 26 is moved to a position such that the cluster gear 28 may he slipped between the cutters on the shafts 2i and 2'! with the individual gears of the cluster intermeshing with the teeth of the respective cutters which are to operate upon said individual gears. When the cluster has been inserted between the cutters until the end thereof adjacent the individual gear 29 bears against the abutment collar 33, then the adjustable rod can be i1 moved inwardly to bring the collar 35 into engagement with the end of the cluster adjacent the gear 32. The apparatus now being set into operation the driven shaft 2| will drive the cutter 24 keyed thereto and said cutter will drive the cluster gear 28 through the individual gear 35 and, in turn, through the individual gears 29, 30

and 32 of the cluster will cause a rotation of all of the cutters 22, 23 and 25 and of the two cutters 24 on the shafts 2?. The support 25 during the rotation of the cutter in mesh with the individual gears of the cluster is moved toward the arm 28 to apply radial pressure between the individual gears and the cutters. The apparatus will be operated in such manner that the individual gears 1 of the cluster and the cutters will rotate in one direction for a predetermined period of time, and then in the opposite direction for a corresponding period of time. When'the cluster gear has been finished the machine is stopped, the support 26 moved outwardly to relieve the pressure between the individual gears and the cutters. As soon as the adjustable rod 36 has been moved out of the way the operator may slip the finished cluster from between the cutters and insert a new and unfinished cluster gear therebetween and repeat the operation upon the new work piece.

The manner in which the cutters operate upon the gears to the cluster to simultaneously shave and burnish the working face surfaces of the teeth thereof is fully explained in my said copending application Serial No. 9,824 and need not be repeated herein, since reference may be had to said application.

In view of the fact that only one of the cutters is driven while the remainder of the cutters are idlers, it is possible to simultaneously finish all of the individual gears of the cluster by means of the combined and simultaneous shaving and burnishing operation, thus effecting a decided reduction in the time required for the finishing of cluster gears with, a consequent increase in production and a lowering of cost.

It will be understood that although the cutters of each of the four groups of sets of cutters are made as identical as it is possible to make them, nevertheless there is a possibility that the three cutters in each group or set will have slight variations. However, since the cluster gear runs in floating intermeshing relationship with the cutters, any slight differences or variations in the cutters will not affect the final correct form of the cluster gear, since each of the individual gears of the cluster will have a composite tooth outline conjugate to all of the three cutters in the group or set of cutters which operate upon it in the finishing operation.

The fact that the cluster gear runs in floating intermeshing engagement with the cutters and that said cutters can be accurately centered upon parallel shafts and act simultaneously upon the individual gears of the cluster during the finishing operation, assures a finished cluster gear wherein the individual gears thereof will have true concentricity with respect to each other.

The manner in which the cutting and burnishing teeth of the cutters act upon the working face surfaces of the teeth of the gears of the cluster is exactly the same as has been described in my said copending application Serial No. 9,824 with reference to the finishing of single gears by means of a plurality of combined burnishing and shaving cutters, such as shown in Figs. 3 and 4 hereof, and, therefore, it is not believed that detailed explanation thereof should be set forth herein. It will be understood that although the cluster gear shown herein is of the helical gear type, as are the cutters for finishing the same, that cluster gears of the spur gear type can equally as well be finished by the present method by the employment of similar cutters of spur gear form.

It will be understood that the invention is not to be limited to the specific illustrations set forth herein, but is susceptible of various modifications and adaptations within the scope of the appended claim.

Having thus described my invention I claim:

The method of simultaneously finishing the individual and different diameter gears of a cluster gear which comprises positioning said cluster gear in floating intermeshing engagement with a plurality of sets of combined burnishing and shaving cutters, each of which sets comprises a plurality of cutters differing in diameter from the cutters of the other sets, the cutters of all the sets of cutters being mounted and accurately centered on shafts parallel to the axis of the cluster gear, the individual gears of the cluster each being in mesh respectively with the cutters of a set of cutters, one cutter of the sets of cutters being arranged to act as a driver and the remainder of the cutters of all of the sets of cutters arranged to act as idlers, rapidly driving the driver cutter to rotate the cluster gear and the other cutters while simultaneously applying relative radial pressure between the cutters and cluster gear to simultaneously burnish and shave the working face surfaces of the individual gears of the cluster.

OLIVER G. SIMMONS. 

